Author(s): R. Aimable; Y. Zech
Linked Author(s):
Keywords: Mixed flow; Air release; Air cavity; Transient flow in pipe; Intermittent flow
Abstract: The problem considered here is related to air-water flows in closed conduits of circular cross-section. Problems as complex as flow transitions can be understood only by identifying the physical mechanisms underlying each transition. Once this is done, a mathematical model that describes each transition can be formulated. The aim of this paper is to present some experimental results on formation of air cavity and intermittent flows in a small-scale laboratory sewer model similar to a reach of a real storm sewer system. In the following, we will describe some observed phenomena and try to explain the instabilities which sometimes occur in real drainage system and could blow-off manhole covers. The explosion of sewer pipes, or drop-shafts, is generally associated with the formation of a sudden air release if the system is ventilated. Moreover, the rising water column can compress the air and cause excessive pressure variations. These observations and many others have been made during the experiments carried out for this work and some of the results are presented in this paper.
Year: 2003